[ubuntu] ubuntu 12.04 suddenly stops connecting to internet via wifi

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HI,
This happens often for my ubuntu 12.04.
I'm using ubuntu on my laptop and connect to internet via wifi.
Sometimes even though the connection is established with the modem I'm unable to connect to the internet.
at that times I'm also unable to connect to 192.168.1.1, which should give me the page to my modem even if there is no internet connection to the modem.
this is the reason for me to belive that ubuntu has a serious connectivity issue.
Since I have dual boot on my laptop (ubuntu 12.04 + Windows 7) I start my system with windows 7 and the problem is gone and I'm able to con
(Hardware)

I recently installed ubuntu 14.04 LTS but am unable to establish an internet connection.My modem is connected via usb and i have had no problems connecting to the internet in windows 7.I have tried setting it up by adding it manually as a mobile broadband connection but nothing happens when i try to connect.The modem im using is a Huawei E5331.I am unable to download any software due to having no

I've a modem (Model : ZTE MF193A), in my modem's manual book I see that the modem support 32 bit ubuntu versions 12.04, 12.10,13.04.

After inserting my modem in my laptop, then minimum 15 minute later I can see my modem as a 'CD-ROM" in my ubuntu 14.04 LTS. Then I have installed the modem driver in my ubuntu. But after rebooting my laptop, ubuntu can't recognize my modem.